The American toad (Anaxyrus americanus) is a common amphibian found throughout eastern North America. Known for its adaptability and distinctive trill, the American toad plays an important role in its ecosystem, particularly through its diet. This article explores the dietary habits of the American toad at various stages of its life, its hunting strategies, and the ecological significance of its feeding behavior.
Range and Subspecies of the American Toad
The American toad (Anaxyrus americanus) is widespread throughout the eastern half of Canada and the United States. The species is divided into three subspecies: the eastern American toad (A. a. americanus), the dwarf American toad (A. a. charlesmithi), and the rare Hudson Bay toad (A. a. copei). These toads are adaptable and can thrive in various environments, from forests to grasslands, provided they have access to fresh water and dense vegetation.
Eastern American Toad
The eastern American toad (A. a. americanus) is a medium-sized toad, typically ranging from 5-9 cm (2.0-3.5 in) in length, with a record length of 11.1 cm (4.4 in). Its color and pattern are variable, with skin color changing depending on habitat, humidity, stress, and temperature. This subspecies has spots that usually contain only one to two warts and enlarged warts on the tibia.
Dwarf American Toad
The dwarf American toad (A. a. charlesmithi) is a smaller version of the American toad, reaching lengths of about 6 cm (2+1⁄4 in). It generally has a dark reddish color, sometimes ranging to light red in isolated populations. The spots on its back are reduced or absent, and when present, they contain a few small red warts with a black ring around them.
Hudson Bay Toad
The Hudson Bay toad (A. a. copei) is a rare Canadian subspecies of A. americanus. It is primarily found in the northern parts of Ontario in isolated populations. These toads often have red coloring on the sides of their bodies and an unusually high number of warts.
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Early Life Diet: From Eggs to Toadlets
The life cycle of the American toad begins with eggs laid in freshwater. The diet changes significantly as the toad develops from an egg to a tadpole and finally into a terrestrial toadlet.
Eggs and Tadpoles
A. americanus eggs are bicolored, typically a roughly equal mixture of black or brown with white or cream. The eggs are deposited in two long ropes, sometimes exceeding 60 meters in length. The American toad lays between 2,000 and 20,000 eggs, which hatch in 3-12 days.
The hatched tadpoles are small and have skinny tails relative to their round black bodies. Studies have shown that tadpoles have a mutualistic relationship with Chlorogonium algae, which accelerates their development. Tadpoles also have mechanisms to reduce predation, such as swimming in shallow water with thick vegetation and producing toxic chemicals in their skin.
Toadlets
Tadpoles reach adulthood in 50-65 days. After metamorphosis, the "toadlets" may stay in the water briefly before transitioning to land. Often, groups of tadpoles reach the toadlet stage simultaneously and migrate to higher ground. Toadlets typically migrate to shaded areas in mid-range and upland forests bordering marshes.
Toadlets eat microscopic bugs in their roaming ground between vegetation. They also consume ants, spiders, slugs, and worms.
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Adult American Toad Diet
Adult American toads are generalist predators with a diet primarily consisting of invertebrates. They are mostly nocturnal, becoming active when it rains. Their diet includes:
- Crickets
- Mealworms
- Earthworms
- Ants
- Spiders
- Slugs
- Centipedes
- Moths
- Other small invertebrates
American toads use their sticky tongues to catch prey. They do not chew their food but swallow it whole, using their forelegs to push larger food items into their mouths.
Hunting Behavior
Adult toads are mostly nocturnal but juveniles are often abroad by day. When it rains, these toads become active and can be observed eating worms and insects. These toads are creatures of habit, preferring to live within an acre of wooded forest with water nearby. They commonly seek cover in burrows, under boardwalks, flat stones, boards, logs, wood piles, or other cover.
Dietary Adaptations
American toads have an innate ability to discern between dangerous and palatable meals. They can weigh their options when encountering potentially poisonous prey, such as specific moths or small salamanders. This selectivity helps them avoid consuming toxic substances.
Captive Diet and Care
American toads are relatively easy to care for in captivity, provided their environmental and dietary needs are met. Replicating the toad's natural environment is essential for its well-being.
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Enclosure and Environment
A single American toad can live comfortably in a 30″ x 12″ x 12″ enclosure, or a 20-gallon long tank. For 2-4 toads, a 36″ x 18″ x 16″ enclosure, or a 40-gallon breeder tank, is needed. The enclosure should have a deep substrate of coconut fiber for burrowing, live leafy plants for hiding, and a shallow dish of dechlorinated water.
Maintaining the correct temperature and humidity is crucial. The temperature in the enclosure can range from the 50s to 80°F. Humidity should be around 50% to 60%.
Feeding in Captivity
Captive American toads should be fed a varied diet of live insects. Live crickets or Dubia roaches should be the main diet, supplemented with earthworms, mealworms, wax worms, and hornworms. Food should be dusted with vitamin and mineral supplements to ensure the toad receives proper nutrition.
Adult toads should be offered three to six food items every other day. Young toads should be fed appropriately sized food items, such as flightless fruit flies and pinhead crickets, daily.
Potential Issues with Captive Feeding
Sometimes, American toads in captivity may refuse to eat. This can be due to improper husbandry, stress, or underlying medical conditions. Ensuring the toad has a suitable environment, proper temperature and humidity, and a varied diet can help stimulate its appetite. If a toad continues to refuse food, a visit to a herp veterinarian is recommended to rule out any health issues.
Ecological Role and Significance
American toads play a crucial role in their ecosystems by controlling populations of insects and other invertebrates. They are widely considered friends to gardeners and farmers due to their consumption of pest insects.
Predators and Defense Mechanisms
Several predators prey on American toads, including snakes, birds, and mammals. Garter snakes are known to specialize in eating toads and are immune to the poisonous secretions of American toads.
To defend themselves, American toads secrete bufotoxin from their parotoid glands, making them unpalatable to many predators. They may also puff up their bodies to appear larger and less attractive as a meal.
Conservation Status
American toads are not currently listed as threatened or endangered. They are adaptable and can thrive in human-modified habitats. However, they are still vulnerable to habitat loss, pollution, and diseases such as chytrid fungus and ranavirus.